You need to have an accurate date of birth in order to post effectively. Here are the Illinois resources for you to contact:

Note: The State of Illinois has a “Confidential Intermediary” search program that will locate and contact birth relatives.

Using a confidential intermediary:
Adopted adults 18 or older and adoptive parents of an adoptee younger than 18 may use the confidential intermediary service. The State of Illinois or the adoption agency that handled your adoption will provide this service. Be aware that the person that is contacted has the right to decline contact and if that happens you will not be given any contact or identifying information to contact them yourself.

Contact the adoption agency that facilitated the adoption or the office below:

ILLINOIS EXPANDS ABILITY OF ALL PARTIES TO USE INTERMEDIARY PROGRAM
Effective January 1, 2004, adopted people 21 and older and adoptive parents can obtain a court-appointed confidential intermediary without proving medical or psychological cause, as they had to under the old law in Illinois. Additionally, birth parents now will be permitted to participate in the intermediary program once the children they placed reach age 21. All parties can access the intermediary program for the purpose of exchanging medical information, obtaining identifying information or arranging contact with mutually consenting biological relatives. Previously, intermediaries could only seek medical information from biological relatives. Provided a "sought-after relative" has not filed a Denial of Information Exchange, the confidential intermediary will inform such relatives of the petitioner's request and of their options. The law also allows adult adoptees access to non-identifying information on original birth certificates and the "actual date and place of birth."

Obtaining Non-Identifying Information: For private adoptions, an adopted adult may obtain non-identifying information. For adoptions facilitated through the State Department of Child and Family Services, adopted adults, birth parents, and adoptive parents may receive non-identifying information.

Using the Adoption Registry: Birth parents, adopted adults 21 or older, adopted adults younger than 21 with the consent of their adoptive parents, and birth siblings 21 or older may use the registry. Adoptive parents, adopted adults, birth parents, and birth siblings* may exchange updated medical information throughout the life of the adopted adult. The registry also may act as an intermediary if either party does not want to be contacted. All parties also may exchange pictures and written statements through the registry. *Note: This rule does not apply for non-relinquished birth siblings looking for a relinquished birth sibling if the birth parents are living and do not give their permission. However, if the birth parents are deceased a non-relinquished sibling can use the registry once they provide the registry with copies of the death certificates of the birth parents.